This research proposal is concerned with the role of chemotaxis in neural crest cell migration, the role of adenosine 3' 5' cyclic monophosphate (cAMP) in chemotaxis and the biochemical control of cAMP levels. I will be working on chemotaxis in the cellular slime mold Dictyostelium discoideum and on two enzymes involved in the metabolism of the chemotactic signal (cAMP), adenylate cyclase and 3'5' cyclic phosphodiesterase. My experiments on 3' 5' cyclic phosphodiesterase involve studies on the function of this enzyme during chemotaxis. I plan to examine the turnover of the enzyme during growth and aggregate formation and compare this with similar studies on non-aggregation temperature sensitive mutants of this organism. My experiments involve a determination of the mechanism of activation of the adenylate cyclase by adenosine 5' monophosphate (AMP), and the regulation of this activity during development by increasing the level of sensitivity of cyclase to AMP stimulation. The methods employed include radioactive assays for enzymatic activities using thin-layer chromatography on ion exchange paper or cellulose sheets. In addition, standard methods of enzyme purification will be employed including centrifugation, precipitation, ion exchange and molecular sieve chromatography. The study will also include an analysis of mutants, so techniques for mutagenesis, cloning and selection of conditional lethal (temperature sensitive) mutants will be employed. BIBLIOGRAPHIC REFERENCES: Rossomando, E. F. and Cutler, L.S. 1975. Localization of Adenylate Cyclase in Dictyostelium discoideum. I. Preparation and Biochemical Characterization of Cell Fractions and Isolated Plasma Membrane Vesicles. Exp. Cell Res. 95:67-78. Cutler, L.S. and Rossomando, E.F. 1975. Localization of Adenylate Cyclase in Dictyostelium discoideum. II. Cytochemical Studies on Whole Cells and Isolated Plasma Membrane Vesicles. Exp. Cell Res. 95: 79-87.